Low-concentration detection of H2S using temperature-dependent Cr-doped cobalt-oxide gas sensors

Among the existing metal-oxide gas sensors, cobalt oxide has the flexibility to revise the morphology through Cr-dopant to enhance sensing properties. Sensitive-surface of the chromium-doped cobalt oxide has proven its effective sensing nature to hydrogen sulfide gas. Interestingly, chromium-dopant increases the surface area, leading to particle size reduce and produces the more active sites for gas molecules. Also, the dopant creates impurity phases on the material which extends the sites for more reaction. To confirms these characteristics, the photoluminescence spectra showed intense peak that mimics the faster transport of electron to accelerate the sensing reaction. According to sensing measurement, the doped sensor is showing three-fold increase of response to 10 ppm gas and also, it detects the 2 ppm efficiently. The doped sensor warrants the stable response to gas due to higher reproducibility. Notably, the doped sensor detects the 1 ppm of gas at 120 s and recovery itself around 200 s. The doped sensor imparts response at room-temperature, affirming sensitive-surface. The doped sensor has shown the capable under humidity environment through response

Fabrication and characterization of Ru-doped LiCuFe2O4 nanoparticles and their capacitive and resistive humidity sensor applications

Polycrystalline ruthenium-doped lithium-copper-ferrite ( Ru-LiCuFe2O4) nanoparticles (NPs) are synthesized using a simple and cost-effective chemical co-precipitation method and annealed at different temperatures for increasing the crystallinity. The transmission and scanning electron microscopy images have confirmed the presence of soft agglomerations and cuboids for the samples annealed at 1100 °C. X-ray photoelectron results along with Raman spectra have collectively demonstrated the presence of Ru in the structure of Ru-LiCuFe2O4 NPs. The dielectric properties of as-synthesized Ru-LiCuFe2O4 NPs are investigated using LCR meter where the smaller NPs demonstrates a higher dielectric constant. Also, the results of magnetic measurements of annealed Ru-LiCuFe2O4 NPs have corroborated a soft magnetic nature due to the pinning sites that endow lower coercivity, remanence and saturation magnetization than that of the pristine one. The variation of permittivity and electrical resistivity with respect to frequency under humidity conditions suggested that this material has a potential to use as capacitive and resistive humidity sensor. The results of this study open the doors for utilization of metal-doped magnetic ferrites for humidity sensing application

Annealing Temperature Effects on Humidity Sensor Properties for Mg_0.5W_0.5Fe₂O₄ Spinel Ferrite

The effects of annealing temperature on the structural, physical and humidity sensing properties of stoichiometric Mg0.5W0.5Fe2O4 spinel ferrite are investigated. In order to highlight the influence of sintering temperature on the structural, magnetic and electrical properties, ferrite samples were sintered for 2 h at 850 °C, 900 °C, 950 °C, 1000 °C and 1050 °C and the physical properties and humidity influence on magnesium-tungsten ferrite materials were analyzed. X-ray diffraction investigations confirmed the formation of magnesium-tungsten ferrite in the analyzed samples. SEM micrographs revealed the influence of annealing temperature on the microstructures of the samples and provided information related to their porosity and crystallite shape and size. This material, treated at different temperatures, is used as an active element in the construction of capacitive and resistive humidity sensors, whose characteristics were also investigated in order to determine the most suitable sintering temperature

Influence of Sb³⁺ Cations on the Structural, Magnetic and Electrical Properties of AlFeO₃ Multiferroic Perovskite with Humidity Sensors Applicative Characteristics

The effects of Sb3+ cations substitution on the structural, magnetic and electrical properties of Al1−xSbxFeO3 multiferroic perovskite are investigated. The partial or total substitution of Al3+ cations with Sb3+ cations, in stoichiometric composition Al1−xSbxFeO3 (x = 0.00, 0.25, 0.50, 0.75 and 1.00) were made in order to identify composite materials with sensors applicative properties. Multiferroic perovskite samples were prepared following technology of the ceramic solid-state method, and the thermal treatments were performed in air atmosphere at 1100 °C temperature. The X-ray diffraction studies have confirmed the phase composition of samples and scanning electron microscopy the shape of the crystallites has been evidenced. The perovskite material was subjected to representative magnetic investigations in order to highlight substitutions characteristics. Investigations on electrical properties have evidenced the substitution dependence of relative permittivity and electrical resistivity under humidity influence and the characteristics of humidity sensors based on this material. The results are discussed in term of microstructural changes induced by the substitutions degree and its sensor applicative effects

Humidity sensors applicative characteristics of granularized and porous Bi 2 O 3 thin films prepared by oxygen plasma-assisted pulsed laser deposition

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